Nucleophilic and Electrophilic Substitution in Aryl Halides

Q.

Aryl halides do not undergo nucleophilic substitution reactions under ordinary conditions because:

1. Carbon carrying halogen atom is sp³ -hybridised

2. The substrate molecule is destabilised due to resonance

3. Partial double bond character between C and X

4. Approach of nucleophile is retarded

Q. In which of following molecules, $\pi$ - electron density in ring is minimum?

1. 
2. 
3. 
4. 

Q.

Toluene when refluxed with $B{r}_2$ in the presence of light mainly gives

1. o-Bromotoluene
2. p-Bromotoluene
3. Benzyl bromide
4. Mixture of o- and p- bromotoluene

Q. Relative reactivity towards SN1 reactionsfor benzyl chloride (1), P- methoxybenzyl chloride (2), P -nitro benzylchloride (3)1) C>A> B(3) B> A> C(2) B> C> A(4) A>C > B

Q. vinylic halide are unreactive towards nucleophilic substitution rxn because of the following except: 1 C-ha\log en bond is strong 2 the ha\log en is bonded to sp2 hybridised carbon 3 a double bond character is developed in carbon ha\log en bond 4 halide ions are not good leaving grps

Q. Benzyl chloride is reacted with different nucleophiles $(H{O}^{-},C{H}_{3}CO{O}^{-},Ph{O}^{-},C{H}_3{O}^{-}).$ Arrange them in the decreasing order of reactivity with Benzyl chloride.

1. $C{H}_3{O}^{-}>H{O}^{-}>Ph{O}^{-}>C{H}_{3}CO{O}^{-}$
2. $H{O}^{-}>C{H}_3{O}^{-}>Ph{O}^{-}>C{H}_{3}CO{O}^{-}$
3. $H{O}^{-}>Ph{O}^{-}>C{H}_3{O}^{-}>C{H}_{3}CO{O}^{-}$
4. $C{H}_{3}CO{O}^{-}>C{H}_3{O}^{-}>H{O}^{-}>Ph{O}^{-}$

Q. Which among the following will react at slowest rate with a nucleophile?

1. 
2. 
3. 
4. 

Q. C-X bond is strongest in

1. $C{H}_{3}F$
2. $C{H}_{3}Cl$
3. $C{H}_{3}Br$
4. $C{H}_{3}I$

Q. formula for ethyl butanoate

Q. Choose the correct $-I$ effect order for halogens when attached to a carbon chain:

1. $-I>-Br>-Cl>-F$
2. $-F>-Cl>-Br>-I$
3. $-Cl>-F>-Br>-I$
4. $-I>-Br>-F>-Cl$

Q. are introduced on benzene ring, the correct order of their inductive effect is:

1. 
2. 
3. 
4. 

Q. In a reaction of $C_6{H}_{5}Y,$ the major product (>60%) is m-isomer, so the group Y is

1. $$-COOH$$
2. $$-N{H}_2$$
3. $$-OH$$
4. $$-Cl$$

Q.

Replacement of Cl of chlorobenzene to give phenol requires drastic conditions but chlorine of 2, 4-dinitrochlorobenzene is readily replaced because

[CBSE PMT

1. NO₂ withdraws e^- from meta position

2. denotes e^- at meta position

3. NO₂ withdraws e^- from ortho/para positions

4. NO₂ make ring electron rich at ortho and para

Q.

Chlorobenzene is

1. Nearly as reactive as methyl chloride

2. More reactive than isopropyl chloride

3. Less reactive than benzyl chloride

4. More reactive than ethyl bromide

Q. Which of the following compounds would liberate $C{O}_2$ on heating?

1. $Pb(OAc{)}_2$
2. $Mg(OAc{)}_2$
3. $Ca(OAc{)}_2$
4. $Ba(OAc{)}_2$

Q.

Which of the following structure is more stable?

1. 

2. 

3. 

4. 

Q.

Neoprene, a synthetic rubber contains which of the following elements besides C and H

1. F

2. N

3. O

4. Cl

Q.

Name the compound which is most reactive towards electrophilic substitution.

Q. The compound Y in the above sequence is

1. Cyclohexene
2. 2-Bromocyclohexylamine
3. 4-Bromocyclohexylamine
4. Cyclohexylamine

Q. Arrange the following sresonating structures in decreasing order of stability:

1. $\left(a\right)>\left(b\right)>\left(c\right)>\left(d\right)$
2. $\left(d\right)>\left(c\right)>\left(b\right)>\left(a\right)$
3. $\left(d\right)>\left(b\right)>\left(c\right)>\left(a\right)$
4. $\left(a\right)>\left(b\right)>\left(d\right)>\left(c\right)$

Q.

Explain the difference between Buna-N and Buna-S.

Q. Toluene when refluxed with $B{r}_2$ in the presence of light mainly gives

1. o-Bromotoluene
2. p-Bromotoluene
3. Mixture of o- and p- bromotoluene
4. Benzyl bromide

Q. Arrangement of $(C{H}_3{)}_3-C-,(C{H}_3{)}_2-C{H}_2-,C{H}_3-C{H}_2-$ when attached to benzyl or an unsaturated group in increasing order of inductive effect is

1. $(C{H}_3{)}_3-C-<(C{H}_3{)}_2-CH-<C{H}_3-C{H}_2-$
2. $C{H}_3-C{H}_2-<(C{H}_3{)}_2-CH-<(C{H}_3{)}_3-C-$
3. $(C{H}_3{)}_2-CH-<(C{H}_3{)}_3-C-<C{H}_3-C{H}_2-$
4. $(C{H}_3{)}_3-C-<C{H}_3-C{H}_2-<(C{H}_3{)}_2-CH-$

Q. Consider the following reaction sequence:
The correct statement regarding X is

1. 
   It has an aldehyde functional group
2. 
   It has both aldehyde and ketone group
3. 
   It has a ketone functiona; group
4. 
   It has ketone and an acid functional group

Q. How many of the following reactions will produce $\text{1-methylcyclohexanol}$as major product?

Q. The compound $C_7{H}_8\stackrel{3C{l}_2/\Delta }{\to }A\stackrel{B{r}_2/Fe}{\to }B\stackrel{Zn/HCl}{\to }C$ The compound C is

1. m-bromotoluene
2. p-bromotoluene
3. 3-bromno-2, 4, 6-trichlorotoluene
4. o-bromotoluene

Q.

Which reaction is used for the preparation of acetophenone?

1. Reimer-Teimann reaction

2. Wurtz-Fittig reaction

3. Friedel-Crafts reaction

4. Cannizzaro’s reaction

Q. 2, 2-dimethyloxirane can be cleaved by :

1. acid
2. water
3. bromine
4. none of the above

Q. 37. In the following pairs which will undergo SN 1 reaction faster: 1)allyl chloride 2)benzyl chloride

Q.
The major product 'P' is :

1. 
2. 
3. 
4.